#include <cstdio>

int main(){
	//freopen("in.txt", "r", stdin);freopen("out.txt", "w", stdout);
	int n;
	char a[101];
	scanf("%d %s", &n, a);
	printf("%c%c", a[0], a[1] );
	for(int i=2;i<n-1;i++){
		if(i%2==0)printf("-");
		printf("%c", a[i] );
	}
	if(n>2)printf("%c", a[n-1] );
	
	return 0;
}
